[XeTeX] How to specify Fontin Sans (has underscore in file names) with Fontspec?

[Philip Taylor (Webmaster, Ret'd)]

Joel C. Salomon wrote:

> Actually this is a real answer; my reading of the fontspec manual
> suggested that the [<style>Font =<whatever>] options needed file names
> rather than font names.  Turns out, not so much:
> 	\documentclass {minimal}
> 	\usepackage {fontspec}
> 	\setmainfont[
> 		BoldFont		= * Bold,
> 		ItalicFont		= * Italic,
> 		BoldItalicFont	= * Bold Italic,
> 		SmallCapsFont	= * Small Caps,
> 		Ligatures = TeX
> 		]{Fontin Sans}
> 	
> 	\begin {document}
> 	foo \textit{foo \textbf{bar};} \textbf{bas} \textsc{quux}
> 	\end {document}
> This works just fine.

I also followed Khaled's suggestion (after downloading
and installing the font, and finding that it still
didn't find it), and Khaled's suggestion also worked
for me, but my code is very different to yours.  Can
you explain how your's works, and why the asterisks
and spaces ?  Mine reads :

     \documentclass [aps] {revtex4}
     \usepackage {fontspec}
	\setmainfont[
  		UprightFont	= FontinSans-Regular,
  		BoldFont	= FontinSans-Bold,
  		ItalicFont	= FontinSans-Italic,
  		BoldItalicFont	= FontinSans-BoldItalic,
  		SmallCapsFont	= FontinSans-SmallCaps,
  		Ligatures = TeX
  		]{Fontin Sans}

     \begin {document}
     The quick brown fox
     \end {document}

Philip Taylor